/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/bpf_perf_event.h>
#include <linux/filter.h>
#include <linux/uaccess.h>
#include <linux/ctype.h>
#include <linux/kprobes.h>
#include <linux/error-injection.h>

#include "trace_probe.h"
#include "trace.h"

u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);

/**
 * trace_call_bpf - invoke BPF program
 * @call: tracepoint event
 * @ctx: opaque context pointer
 *
 * kprobe handlers execute BPF programs via this helper.
 * Can be used from static tracepoints in the future.
 *
 * Return: BPF programs always return an integer which is interpreted by
 * kprobe handler as:
 * 0 - return from kprobe (event is filtered out)
 * 1 - store kprobe event into ring buffer
 * Other values are reserved and currently alias to 1
 */
unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
{
        unsigned int ret;

        if (in_nmi()) /* not supported yet */
                return 1;

        preempt_disable();

        if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
                /*
                 * since some bpf program is already running on this cpu,
                 * don't call into another bpf program (same or different)
                 * and don't send kprobe event into ring-buffer,
                 * so return zero here
                 */
                ret = 0;
                goto out;
        }

        /*
         * Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock
         * to all call sites, we did a bpf_prog_array_valid() there to check
         * whether call->prog_array is empty or not, which is
         * a heurisitc to speed up execution.
         *
         * If bpf_prog_array_valid() fetched prog_array was
         * non-NULL, we go into trace_call_bpf() and do the actual
         * proper rcu_dereference() under RCU lock.
         * If it turns out that prog_array is NULL then, we bail out.
         * For the opposite, if the bpf_prog_array_valid() fetched pointer
         * was NULL, you'll skip the prog_array with the risk of missing
         * out of events when it was updated in between this and the
         * rcu_dereference() which is accepted risk.
         */
        ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN);

 out:
        __this_cpu_dec(bpf_prog_active);
        preempt_enable();

        return ret;
}
EXPORT_SYMBOL_GPL(trace_call_bpf);

#ifdef CONFIG_BPF_KPROBE_OVERRIDE
BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc)
{
        regs_set_return_value(regs, rc);
        override_function_with_return(regs);
        return 0;
}

static const struct bpf_func_proto bpf_override_return_proto = {
        .func           = bpf_override_return,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_ANYTHING,
};
#endif

BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
{
        int ret;

        ret = probe_kernel_read(dst, unsafe_ptr, size);
        if (unlikely(ret < 0))
                memset(dst, 0, size);

        return ret;
}

static const struct bpf_func_proto bpf_probe_read_proto = {
        .func           = bpf_probe_read,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
        .arg3_type      = ARG_ANYTHING,
};

BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
           u32, size)
{
        /*
         * Ensure we're in user context which is safe for the helper to
         * run. This helper has no business in a kthread.
         *
         * access_ok() should prevent writing to non-user memory, but in
         * some situations (nommu, temporary switch, etc) access_ok() does
         * not provide enough validation, hence the check on KERNEL_DS.
         */

        if (unlikely(in_interrupt() ||
                     current->flags & (PF_KTHREAD | PF_EXITING)))
                return -EPERM;
        if (unlikely(uaccess_kernel()))
                return -EPERM;
        if (!access_ok(VERIFY_WRITE, unsafe_ptr, size))
                return -EPERM;

        return probe_kernel_write(unsafe_ptr, src, size);
}

static const struct bpf_func_proto bpf_probe_write_user_proto = {
        .func           = bpf_probe_write_user,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_ANYTHING,
        .arg2_type      = ARG_PTR_TO_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
{
        pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
                            current->comm, task_pid_nr(current));

        return &bpf_probe_write_user_proto;
}

/*
 * Only limited trace_printk() conversion specifiers allowed:
 * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
 */
BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
           u64, arg2, u64, arg3)
{
        bool str_seen = false;
        int mod[3] = {};
        int fmt_cnt = 0;
        u64 unsafe_addr;
        char buf[64];
        int i;

        /*
         * bpf_check()->check_func_arg()->check_stack_boundary()
         * guarantees that fmt points to bpf program stack,
         * fmt_size bytes of it were initialized and fmt_size > 0
         */
        if (fmt[--fmt_size] != 0)
                return -EINVAL;

        /* check format string for allowed specifiers */
        for (i = 0; i < fmt_size; i++) {
                if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
                        return -EINVAL;

                if (fmt[i] != '%')
                        continue;

                if (fmt_cnt >= 3)
                        return -EINVAL;

                /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
                i++;
                if (fmt[i] == 'l') {
                        mod[fmt_cnt]++;
                        i++;
                } else if (fmt[i] == 'p' || fmt[i] == 's') {
                        mod[fmt_cnt]++;
                        i++;
                        if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
                                return -EINVAL;
                        fmt_cnt++;
                        if (fmt[i - 1] == 's') {
                                if (str_seen)
                                        /* allow only one '%s' per fmt string */
                                        return -EINVAL;
                                str_seen = true;

                                switch (fmt_cnt) {
                                case 1:
                                        unsafe_addr = arg1;
                                        arg1 = (long) buf;
                                        break;
                                case 2:
                                        unsafe_addr = arg2;
                                        arg2 = (long) buf;
                                        break;
                                case 3:
                                        unsafe_addr = arg3;
                                        arg3 = (long) buf;
                                        break;
                                }
                                buf[0] = 0;
                                strncpy_from_unsafe(buf,
                                                    (void *) (long) unsafe_addr,
                                                    sizeof(buf));
                        }
                        continue;
                }

                if (fmt[i] == 'l') {
                        mod[fmt_cnt]++;
                        i++;
                }

                if (fmt[i] != 'i' && fmt[i] != 'd' &&
                    fmt[i] != 'u' && fmt[i] != 'x')
                        return -EINVAL;
                fmt_cnt++;
        }

/* Horrid workaround for getting va_list handling working with different
 * argument type combinations generically for 32 and 64 bit archs.
 */
#define __BPF_TP_EMIT() __BPF_ARG3_TP()
#define __BPF_TP(...)                                                   \
        __trace_printk(0 /* Fake ip */,                                 \
                       fmt, ##__VA_ARGS__)

#define __BPF_ARG1_TP(...)                                              \
        ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64))        \
          ? __BPF_TP(arg1, ##__VA_ARGS__)                               \
          : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32))    \
              ? __BPF_TP((long)arg1, ##__VA_ARGS__)                     \
              : __BPF_TP((u32)arg1, ##__VA_ARGS__)))

#define __BPF_ARG2_TP(...)                                              \
        ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64))        \
          ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__)                          \
          : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32))    \
              ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__)                \
              : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))

#define __BPF_ARG3_TP(...)                                              \
        ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64))        \
          ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__)                          \
          : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32))    \
              ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__)                \
              : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))

        return __BPF_TP_EMIT();
}

static const struct bpf_func_proto bpf_trace_printk_proto = {
        .func           = bpf_trace_printk,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_MEM,
        .arg2_type      = ARG_CONST_SIZE,
};

const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
{
        /*
         * this program might be calling bpf_trace_printk,
         * so allocate per-cpu printk buffers
         */
        trace_printk_init_buffers();

        return &bpf_trace_printk_proto;
}

static __always_inline int
get_map_perf_counter(struct bpf_map *map, u64 flags,
                     u64 *value, u64 *enabled, u64 *running)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        unsigned int cpu = smp_processor_id();
        u64 index = flags & BPF_F_INDEX_MASK;
        struct bpf_event_entry *ee;

        if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
                return -EINVAL;
        if (index == BPF_F_CURRENT_CPU)
                index = cpu;
        if (unlikely(index >= array->map.max_entries))
                return -E2BIG;

        ee = READ_ONCE(array->ptrs[index]);
        if (!ee)
                return -ENOENT;

        return perf_event_read_local(ee->event, value, enabled, running);
}

BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
{
        u64 value = 0;
        int err;

        err = get_map_perf_counter(map, flags, &value, NULL, NULL);
        /*
         * this api is ugly since we miss [-22..-2] range of valid
         * counter values, but that's uapi
         */
        if (err)
                return err;
        return value;
}

static const struct bpf_func_proto bpf_perf_event_read_proto = {
        .func           = bpf_perf_event_read,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_ANYTHING,
};

BPF_CALL_4(bpf_perf_event_read_value, struct bpf_map *, map, u64, flags,
           struct bpf_perf_event_value *, buf, u32, size)
{
        int err = -EINVAL;

        if (unlikely(size != sizeof(struct bpf_perf_event_value)))
                goto clear;
        err = get_map_perf_counter(map, flags, &buf->counter, &buf->enabled,
                                   &buf->running);
        if (unlikely(err))
                goto clear;
        return 0;
clear:
        memset(buf, 0, size);
        return err;
}

static const struct bpf_func_proto bpf_perf_event_read_value_proto = {
        .func           = bpf_perf_event_read_value,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_ANYTHING,
        .arg3_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg4_type      = ARG_CONST_SIZE,
};

static DEFINE_PER_CPU(struct perf_sample_data, bpf_trace_sd);

static __always_inline u64
__bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
                        u64 flags, struct perf_sample_data *sd)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        unsigned int cpu = smp_processor_id();
        u64 index = flags & BPF_F_INDEX_MASK;
        struct bpf_event_entry *ee;
        struct perf_event *event;

        if (index == BPF_F_CURRENT_CPU)
                index = cpu;
        if (unlikely(index >= array->map.max_entries))
                return -E2BIG;

        ee = READ_ONCE(array->ptrs[index]);
        if (!ee)
                return -ENOENT;

        event = ee->event;
        if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
                     event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
                return -EINVAL;

        if (unlikely(event->oncpu != cpu))
                return -EOPNOTSUPP;

        perf_event_output(event, sd, regs);
        return 0;
}

BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
           u64, flags, void *, data, u64, size)
{
        struct perf_sample_data *sd = this_cpu_ptr(&bpf_trace_sd);
        struct perf_raw_record raw = {
                .frag = {
                        .size = size,
                        .data = data,
                },
        };

        if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
                return -EINVAL;

        perf_sample_data_init(sd, 0, 0);
        sd->raw = &raw;

        return __bpf_perf_event_output(regs, map, flags, sd);
}

static const struct bpf_func_proto bpf_perf_event_output_proto = {
        .func           = bpf_perf_event_output,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_MEM,
        .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
};

static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
static DEFINE_PER_CPU(struct perf_sample_data, bpf_misc_sd);

u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
                     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
{
        struct perf_sample_data *sd = this_cpu_ptr(&bpf_misc_sd);
        struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
        struct perf_raw_frag frag = {
                .copy           = ctx_copy,
                .size           = ctx_size,
                .data           = ctx,
        };
        struct perf_raw_record raw = {
                .frag = {
                        {
                                .next   = ctx_size ? &frag : NULL,
                        },
                        .size   = meta_size,
                        .data   = meta,
                },
        };

        perf_fetch_caller_regs(regs);
        perf_sample_data_init(sd, 0, 0);
        sd->raw = &raw;

        return __bpf_perf_event_output(regs, map, flags, sd);
}

BPF_CALL_0(bpf_get_current_task)
{
        return (long) current;
}

static const struct bpf_func_proto bpf_get_current_task_proto = {
        .func           = bpf_get_current_task,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        struct cgroup *cgrp;

        if (unlikely(in_interrupt()))
                return -EINVAL;
        if (unlikely(idx >= array->map.max_entries))
                return -E2BIG;

        cgrp = READ_ONCE(array->ptrs[idx]);
        if (unlikely(!cgrp))
                return -EAGAIN;

        return task_under_cgroup_hierarchy(current, cgrp);
}

static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
        .func           = bpf_current_task_under_cgroup,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_ANYTHING,
};

BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
           const void *, unsafe_ptr)
{
        int ret;

        /*
         * The strncpy_from_unsafe() call will likely not fill the entire
         * buffer, but that's okay in this circumstance as we're probing
         * arbitrary memory anyway similar to bpf_probe_read() and might
         * as well probe the stack. Thus, memory is explicitly cleared
         * only in error case, so that improper users ignoring return
         * code altogether don't copy garbage; otherwise length of string
         * is returned that can be used for bpf_perf_event_output() et al.
         */
        ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
        if (unlikely(ret < 0))
                memset(dst, 0, size);

        return ret;
}

static const struct bpf_func_proto bpf_probe_read_str_proto = {
        .func           = bpf_probe_read_str,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
        .arg3_type      = ARG_ANYTHING,
};

static const struct bpf_func_proto *
tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_map_lookup_elem:
                return &bpf_map_lookup_elem_proto;
        case BPF_FUNC_map_update_elem:
                return &bpf_map_update_elem_proto;
        case BPF_FUNC_map_delete_elem:
                return &bpf_map_delete_elem_proto;
        case BPF_FUNC_probe_read:
                return &bpf_probe_read_proto;
        case BPF_FUNC_ktime_get_ns:
                return &bpf_ktime_get_ns_proto;
        case BPF_FUNC_tail_call:
                return &bpf_tail_call_proto;
        case BPF_FUNC_get_current_pid_tgid:
                return &bpf_get_current_pid_tgid_proto;
        case BPF_FUNC_get_current_task:
                return &bpf_get_current_task_proto;
        case BPF_FUNC_get_current_uid_gid:
                return &bpf_get_current_uid_gid_proto;
        case BPF_FUNC_get_current_comm:
                return &bpf_get_current_comm_proto;
        case BPF_FUNC_trace_printk:
                return bpf_get_trace_printk_proto();
        case BPF_FUNC_get_smp_processor_id:
                return &bpf_get_smp_processor_id_proto;
        case BPF_FUNC_get_numa_node_id:
                return &bpf_get_numa_node_id_proto;
        case BPF_FUNC_perf_event_read:
                return &bpf_perf_event_read_proto;
        case BPF_FUNC_probe_write_user:
                return bpf_get_probe_write_proto();
        case BPF_FUNC_current_task_under_cgroup:
                return &bpf_current_task_under_cgroup_proto;
        case BPF_FUNC_get_prandom_u32:
                return &bpf_get_prandom_u32_proto;
        case BPF_FUNC_probe_read_str:
                return &bpf_probe_read_str_proto;
        default:
                return NULL;
        }
}

static const struct bpf_func_proto *
kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_perf_event_output:
                return &bpf_perf_event_output_proto;
        case BPF_FUNC_get_stackid:
                return &bpf_get_stackid_proto;
        case BPF_FUNC_perf_event_read_value:
                return &bpf_perf_event_read_value_proto;
#ifdef CONFIG_BPF_KPROBE_OVERRIDE
        case BPF_FUNC_override_return:
                return &bpf_override_return_proto;
#endif
        default:
                return tracing_func_proto(func_id, prog);
        }
}

/* bpf+kprobe programs can access fields of 'struct pt_regs' */
static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
                                        const struct bpf_prog *prog,
                                        struct bpf_insn_access_aux *info)
{
        if (off < 0 || off >= sizeof(struct pt_regs))
                return false;
        if (type != BPF_READ)
                return false;
        if (off % size != 0)
                return false;
        /*
         * Assertion for 32 bit to make sure last 8 byte access
         * (BPF_DW) to the last 4 byte member is disallowed.
         */
        if (off + size > sizeof(struct pt_regs))
                return false;

        return true;
}

const struct bpf_verifier_ops kprobe_verifier_ops = {
        .get_func_proto  = kprobe_prog_func_proto,
        .is_valid_access = kprobe_prog_is_valid_access,
};

const struct bpf_prog_ops kprobe_prog_ops = {
};

BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
           u64, flags, void *, data, u64, size)
{
        struct pt_regs *regs = *(struct pt_regs **)tp_buff;

        /*
         * r1 points to perf tracepoint buffer where first 8 bytes are hidden
         * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
         * from there and call the same bpf_perf_event_output() helper inline.
         */
        return ____bpf_perf_event_output(regs, map, flags, data, size);
}

static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
        .func           = bpf_perf_event_output_tp,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_MEM,
        .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
};

BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
           u64, flags)
{
        struct pt_regs *regs = *(struct pt_regs **)tp_buff;

        /*
         * Same comment as in bpf_perf_event_output_tp(), only that this time
         * the other helper's function body cannot be inlined due to being
         * external, thus we need to call raw helper function.
         */
        return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
                               flags, 0, 0);
}

static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
        .func           = bpf_get_stackid_tp,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
};

static const struct bpf_func_proto *
tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_perf_event_output:
                return &bpf_perf_event_output_proto_tp;
        case BPF_FUNC_get_stackid:
                return &bpf_get_stackid_proto_tp;
        default:
                return tracing_func_proto(func_id, prog);
        }
}

static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
                                    const struct bpf_prog *prog,
                                    struct bpf_insn_access_aux *info)
{
        if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
                return false;
        if (type != BPF_READ)
                return false;
        if (off % size != 0)
                return false;

        BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
        return true;
}

const struct bpf_verifier_ops tracepoint_verifier_ops = {
        .get_func_proto  = tp_prog_func_proto,
        .is_valid_access = tp_prog_is_valid_access,
};

const struct bpf_prog_ops tracepoint_prog_ops = {
};

BPF_CALL_3(bpf_perf_prog_read_value, struct bpf_perf_event_data_kern *, ctx,
           struct bpf_perf_event_value *, buf, u32, size)
{
        int err = -EINVAL;

        if (unlikely(size != sizeof(struct bpf_perf_event_value)))
                goto clear;
        err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled,
                                    &buf->running);
        if (unlikely(err))
                goto clear;
        return 0;
clear:
        memset(buf, 0, size);
        return err;
}

static const struct bpf_func_proto bpf_perf_prog_read_value_proto = {
         .func           = bpf_perf_prog_read_value,
         .gpl_only       = true,
         .ret_type       = RET_INTEGER,
         .arg1_type      = ARG_PTR_TO_CTX,
         .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
         .arg3_type      = ARG_CONST_SIZE,
};

static const struct bpf_func_proto *
pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_perf_event_output:
                return &bpf_perf_event_output_proto_tp;
        case BPF_FUNC_get_stackid:
                return &bpf_get_stackid_proto_tp;
        case BPF_FUNC_perf_prog_read_value:
                return &bpf_perf_prog_read_value_proto;
        default:
                return tracing_func_proto(func_id, prog);
        }
}

/*
 * bpf_raw_tp_regs are separate from bpf_pt_regs used from skb/xdp
 * to avoid potential recursive reuse issue when/if tracepoints are added
 * inside bpf_*_event_output and/or bpf_get_stack_id
 */
static DEFINE_PER_CPU(struct pt_regs, bpf_raw_tp_regs);
BPF_CALL_5(bpf_perf_event_output_raw_tp, struct bpf_raw_tracepoint_args *, args,
           struct bpf_map *, map, u64, flags, void *, data, u64, size)
{
        struct pt_regs *regs = this_cpu_ptr(&bpf_raw_tp_regs);

        perf_fetch_caller_regs(regs);
        return ____bpf_perf_event_output(regs, map, flags, data, size);
}

static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = {
        .func           = bpf_perf_event_output_raw_tp,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_MEM,
        .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
};

BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args,
           struct bpf_map *, map, u64, flags)
{
        struct pt_regs *regs = this_cpu_ptr(&bpf_raw_tp_regs);

        perf_fetch_caller_regs(regs);
        /* similar to bpf_perf_event_output_tp, but pt_regs fetched differently */
        return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
                               flags, 0, 0);
}

static const struct bpf_func_proto bpf_get_stackid_proto_raw_tp = {
        .func           = bpf_get_stackid_raw_tp,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
};

static const struct bpf_func_proto *
raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_perf_event_output:
                return &bpf_perf_event_output_proto_raw_tp;
        case BPF_FUNC_get_stackid:
                return &bpf_get_stackid_proto_raw_tp;
        default:
                return tracing_func_proto(func_id, prog);
        }
}

static bool raw_tp_prog_is_valid_access(int off, int size,
                                        enum bpf_access_type type,
                                        const struct bpf_prog *prog,
                                        struct bpf_insn_access_aux *info)
{
        /* largest tracepoint in the kernel has 12 args */
        if (off < 0 || off >= sizeof(__u64) * 12)
                return false;
        if (type != BPF_READ)
                return false;
        if (off % size != 0)
                return false;
        return true;
}

const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {
        .get_func_proto  = raw_tp_prog_func_proto,
        .is_valid_access = raw_tp_prog_is_valid_access,
};

const struct bpf_prog_ops raw_tracepoint_prog_ops = {
};

static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
                                    const struct bpf_prog *prog,
                                    struct bpf_insn_access_aux *info)
{
        const int size_u64 = sizeof(u64);

        if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
                return false;
        if (type != BPF_READ)
                return false;
        if (off % size != 0)
                return false;

        switch (off) {
        case bpf_ctx_range(struct bpf_perf_event_data, sample_period):
                bpf_ctx_record_field_size(info, size_u64);
                if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
                        return false;
                break;
        case bpf_ctx_range(struct bpf_perf_event_data, addr):
                bpf_ctx_record_field_size(info, size_u64);
                if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
                        return false;
                break;
        default:
                if (size != sizeof(long))
                        return false;
        }

        return true;
}

static u32 pe_prog_convert_ctx_access(enum bpf_access_type type,
                                      const struct bpf_insn *si,
                                      struct bpf_insn *insn_buf,
                                      struct bpf_prog *prog, u32 *target_size)
{
        struct bpf_insn *insn = insn_buf;

        switch (si->off) {
        case offsetof(struct bpf_perf_event_data, sample_period):
                *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
                                                       data), si->dst_reg, si->src_reg,
                                      offsetof(struct bpf_perf_event_data_kern, data));
                *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
                                      bpf_target_off(struct perf_sample_data, period, 8,
                                                     target_size));
                break;
        case offsetof(struct bpf_perf_event_data, addr):
                *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
                                                       data), si->dst_reg, si->src_reg,
                                      offsetof(struct bpf_perf_event_data_kern, data));
                *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
                                      bpf_target_off(struct perf_sample_data, addr, 8,
                                                     target_size));
                break;
        default:
                *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
                                                       regs), si->dst_reg, si->src_reg,
                                      offsetof(struct bpf_perf_event_data_kern, regs));
                *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
                                      si->off);
                break;
        }

        return insn - insn_buf;
}

const struct bpf_verifier_ops perf_event_verifier_ops = {
        .get_func_proto         = pe_prog_func_proto,
        .is_valid_access        = pe_prog_is_valid_access,
        .convert_ctx_access     = pe_prog_convert_ctx_access,
};

const struct bpf_prog_ops perf_event_prog_ops = {
};

static DEFINE_MUTEX(bpf_event_mutex);

#define BPF_TRACE_MAX_PROGS 64

int perf_event_attach_bpf_prog(struct perf_event *event,
                               struct bpf_prog *prog)
{
        struct bpf_prog_array __rcu *old_array;
        struct bpf_prog_array *new_array;
        int ret = -EEXIST;

        /*
         * Kprobe override only works if they are on the function entry,
         * and only if they are on the opt-in list.
         */
        if (prog->kprobe_override &&
            (!trace_kprobe_on_func_entry(event->tp_event) ||
             !trace_kprobe_error_injectable(event->tp_event)))
                return -EINVAL;

        mutex_lock(&bpf_event_mutex);

        if (event->prog)
                goto unlock;

        old_array = event->tp_event->prog_array;
        if (old_array &&
            bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
                ret = -E2BIG;
                goto unlock;
        }

        ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
        if (ret < 0)
                goto unlock;

        /* set the new array to event->tp_event and set event->prog */
        event->prog = prog;
        rcu_assign_pointer(event->tp_event->prog_array, new_array);
        bpf_prog_array_free(old_array);

unlock:
        mutex_unlock(&bpf_event_mutex);
        return ret;
}

void perf_event_detach_bpf_prog(struct perf_event *event)
{
        struct bpf_prog_array __rcu *old_array;
        struct bpf_prog_array *new_array;
        int ret;

        mutex_lock(&bpf_event_mutex);

        if (!event->prog)
                goto unlock;

        old_array = event->tp_event->prog_array;
        ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
        if (ret < 0) {
                bpf_prog_array_delete_safe(old_array, event->prog);
        } else {
                rcu_assign_pointer(event->tp_event->prog_array, new_array);
                bpf_prog_array_free(old_array);
        }

        bpf_prog_put(event->prog);
        event->prog = NULL;

unlock:
        mutex_unlock(&bpf_event_mutex);
}

int perf_event_query_prog_array(struct perf_event *event, void __user *info)
{
        struct perf_event_query_bpf __user *uquery = info;
        struct perf_event_query_bpf query = {};
        u32 *ids, prog_cnt, ids_len;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (event->attr.type != PERF_TYPE_TRACEPOINT)
                return -EINVAL;
        if (copy_from_user(&query, uquery, sizeof(query)))
                return -EFAULT;

        ids_len = query.ids_len;
        if (ids_len > BPF_TRACE_MAX_PROGS)
                return -E2BIG;
        ids = kcalloc(ids_len, sizeof(u32), GFP_USER | __GFP_NOWARN);
        if (!ids)
                return -ENOMEM;
        /*
         * The above kcalloc returns ZERO_SIZE_PTR when ids_len = 0, which
         * is required when user only wants to check for uquery->prog_cnt.
         * There is no need to check for it since the case is handled
         * gracefully in bpf_prog_array_copy_info.

         */

        mutex_lock(&bpf_event_mutex);
        ret = bpf_prog_array_copy_info(event->tp_event->prog_array,
                                       ids,
                                       ids_len,
                                       &prog_cnt);
        mutex_unlock(&bpf_event_mutex);

        if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) ||
            copy_to_user(uquery->ids, ids, ids_len * sizeof(u32)))
                ret = -EFAULT;

        kfree(ids);
        return ret;
}

extern struct bpf_raw_event_map __start__bpf_raw_tp[];
extern struct bpf_raw_event_map __stop__bpf_raw_tp[];

struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
{
        struct bpf_raw_event_map *btp = __start__bpf_raw_tp;

        for (; btp < __stop__bpf_raw_tp; btp++) {
                if (!strcmp(btp->tp->name, name))
                        return btp;
        }
        return NULL;
}

static __always_inline
void __bpf_trace_run(struct bpf_prog *prog, u64 *args)
{
        rcu_read_lock();
        preempt_disable();
        (void) BPF_PROG_RUN(prog, args);
        preempt_enable();
        rcu_read_unlock();
}

#define UNPACK(...)                     __VA_ARGS__
#define REPEAT_1(FN, DL, X, ...)        FN(X)
#define REPEAT_2(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_1(FN, DL, __VA_ARGS__)
#define REPEAT_3(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_2(FN, DL, __VA_ARGS__)
#define REPEAT_4(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_3(FN, DL, __VA_ARGS__)
#define REPEAT_5(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_4(FN, DL, __VA_ARGS__)
#define REPEAT_6(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_5(FN, DL, __VA_ARGS__)
#define REPEAT_7(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_6(FN, DL, __VA_ARGS__)
#define REPEAT_8(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_7(FN, DL, __VA_ARGS__)
#define REPEAT_9(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_8(FN, DL, __VA_ARGS__)
#define REPEAT_10(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_9(FN, DL, __VA_ARGS__)
#define REPEAT_11(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_10(FN, DL, __VA_ARGS__)
#define REPEAT_12(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_11(FN, DL, __VA_ARGS__)
#define REPEAT(X, FN, DL, ...)          REPEAT_##X(FN, DL, __VA_ARGS__)

#define SARG(X)         u64 arg##X
#define COPY(X)         args[X] = arg##X

#define __DL_COM        (,)
#define __DL_SEM        (;)

#define __SEQ_0_11      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

#define BPF_TRACE_DEFN_x(x)                                             \
        void bpf_trace_run##x(struct bpf_prog *prog,                    \
                              REPEAT(x, SARG, __DL_COM, __SEQ_0_11))    \
        {                                                               \
                u64 args[x];                                            \
                REPEAT(x, COPY, __DL_SEM, __SEQ_0_11);                  \
                __bpf_trace_run(prog, args);                            \
        }                                                               \
        EXPORT_SYMBOL_GPL(bpf_trace_run##x)
BPF_TRACE_DEFN_x(1);
BPF_TRACE_DEFN_x(2);
BPF_TRACE_DEFN_x(3);
BPF_TRACE_DEFN_x(4);
BPF_TRACE_DEFN_x(5);
BPF_TRACE_DEFN_x(6);
BPF_TRACE_DEFN_x(7);
BPF_TRACE_DEFN_x(8);
BPF_TRACE_DEFN_x(9);
BPF_TRACE_DEFN_x(10);
BPF_TRACE_DEFN_x(11);
BPF_TRACE_DEFN_x(12);

static int __bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
        struct tracepoint *tp = btp->tp;

        /*
         * check that program doesn't access arguments beyond what's
         * available in this tracepoint
         */
        if (prog->aux->max_ctx_offset > btp->num_args * sizeof(u64))
                return -EINVAL;

        return tracepoint_probe_register(tp, (void *)btp->bpf_func, prog);
}

int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
        int err;

        mutex_lock(&bpf_event_mutex);
        err = __bpf_probe_register(btp, prog);
        mutex_unlock(&bpf_event_mutex);
        return err;
}

int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
        int err;

        mutex_lock(&bpf_event_mutex);
        err = tracepoint_probe_unregister(btp->tp, (void *)btp->bpf_func, prog);
        mutex_unlock(&bpf_event_mutex);
        return err;
}